As general manager of global research for Hitwise, an online market research firm, Bill Tancer monitors the daily online behavior of more than 10 million internet users, tracking what, when and how they search. In the past, businesses relied solely on surveys to understand consumer behavior, explains Tancer, but examining "actual behavior is much more insightful than asking people how they behave. To market effectively today, you have to understand how your potential customers are behaving online."

So how are they behaving? "Our data often reveals that people think about things earlier and in slightly different ways than we think they do," says Tancer, author of Click: What Millions of People Do Online and Why It Matters. "As an entrepreneur, you want to know this because you want to be in front of consumers then." He points to an example involving prom dresses: Boutiques typically start marketing to buyers in March, yet data shows that buyers start shopping as early as January.

Looking to paid companies like Hitwise or free data sources like Google Trends are options, but Tancer also emphasizes paying close attention to your own site-centric data, search logs and click streams.